Economic assessment methods for transmission network expansion planning in competitive environments

The optimal transmission system expansion planning is an important part of the overall planning task of electric power system under competitive electricity market environments. As we knew reliability indices for evaluation of the transmission expansion plans are quite mature; but, there is not an exhaustive framework for the economic appraisal of the transmission expansion plans. Therefore, survey on the existing economic appraisal methods and proper classification of them would be very advantageous for the researchers in this area. In addition, in order to rate the effect of future investments in transmission, we need to define a set of indices that show the benefits obtained by the different agents of the market including generators, demands, and the transmission entity. In this paper we classify economic indices in three categories including producer, consumer, and system operator (owner) viewpoint. Each category is composed of several indices which are defined in different system levels. All indices computed and compared for two different expansion plans which have been applied to IEEE 24-bus Reliability Test System. Planning results of transmission network expansion process can be construed in economic terms based on the values of the obtained indices for various scenarios, parameters, and topologies.